The deputy leader of al-Qaeda’s affiliate in Yemen was killed in an airstrike Monday, according to the Yemeni government, five years after he was released from the U.S. prison in Guantanamo Bay in a failed attempt at rehabilitation.

Said Ali al-Shihri, a Saudi national and the deputy emir of al-Qaeda in the Arabian Peninsula, and six other people were killed in a military operation in the southern Yemeni province of Hadramaut, the Yemeni Defense Ministry said in a brief statement.

Yemeni officials gave few details about how Shihri died, but the U.S. military and the CIA have intensified their campaign of drone attacks in Yemen this year.

The Associated Press reported that two senior U.S. officials in Washington had confirmed Shihri’s death. His demise has been erroneously reported in the past, however, and other U.S. officials told The Washington Post that they were awaiting further evidence that Shihri was killed.

Shihri was captured in Afghanistan in December 2001 and spent nearly six years as a prisoner at Guantanamo. He was released to the custody of the Saudi government as part of a rehabilitation program for militants. In 2008, however, he decamped for Yemen and helped to revive al-Qaeda’s organization there.